The present invention refers a dental device comprising an abrasive disk having a hub and a spindle with a collet, the opening of the hub and the cross section of the collet being complementary to each other in order to get a removable fastening of the abrasive disk on the spindle.
A plurality of dental instruments are already known which are used for the treatment of dental fillings, this work being typically carried out in several steps, beginning with rough-working until fine polishing. In these operations, it is necessary to use different abrasive disks, and different devices are at hand to carry out the exchange of the tool in a simple and rapid manner. Systems having non-positive or positive connection have been proven as useful.
U.S. Pat. No. 4,889,489 discloses a dental device in which the spindle has a square end, and the hub of the abrasive disk has a corresponding four-edged opening in order to achieve a positive coupling. The device allows to transmit a higher torque but has the drawback that the abrasive disk, when it is to be connected with the spindle, must always be brought into a correct position with respect to the spindle.
U.S. Pat. No. 4,988,294 discloses another dental device in which the free end of the spindle is rotationally symmetrically shaped and provided with slots in order to receive a hard hub being also rotationally symmetrically shaped. The slotted end of the spindle is spread out by the action of the centrifugal force generated by the rotation of the spindle, and the disk is retained on the spindle. However, the torque which can be transmitted is rather small whereas the disk can be inserted on the end of the spindle in any position whatsoever.